l()0 LANGUAGE AND MENTAL DEVELOPMENT OF CHILDREN

increasing use of terms of increasing generality. These show
clearly enough the extent to which the child who employs them
has successfully classified and systematized the concrete particulars
of his world. An ordered system of knowledge is characterized
by its ascending levels of generality. At the top arc the abstract
ideas that are least involved in the particulars to which they relate.
Thus, as Professor Whitchead has said :l

Classification is a half-way house between the immediate con-
cretencss of the individual thing and the complete abstraction of
mathematical notions. The species take account of the specific
character, and the genera of the generic character. But in the
procedure of relating mathematical notions to the facts of nature,
by counting, by measurement, and by geometrical relations, and
by types of order, the rational contemplation is lifted from the
incomplete abstractions involved in definite species and genera, to
the complete abstractions of mathematics. But unless you can
progress from classification to mathematics your reasoning cattnot
take you far.

13* PRACTICE IN VERBAL DEFINITION
An interesting game which intelligent children will enjoy
playing is that of identifying objects from their dictionary defini-
tions: for example, they will experience little difficulty if they
are asked to name a juicy, deep-golden, thick-skinned fruit, or to say
what a frame of metal bars for holding fuel in a fireplace is called* This
game is the more exacting when it is difficult to frame a satis-
factory definition without a phrase or two to indicate the use
to which the object spoken of is put. Thus, a light folding framework
of flexible ribs of steel, radiating from and sliding up and down a stick,
and covered with silk^ is perhaps enough to give bright children the
idea of umbrella, but others may need added a phrase like and
carried above the head as a protection against rain befo're they can
identify the object so described. Most children will recognize
a piece of household furniture consisting of aflat surface supported on legs
as the description of a table without further specification, but
a short stiff pointed piece of wire with flattened head is not enough as a
rule to make for its speedy recftgnition as the description of a pin.
This kind of exercise can be made to lead to a great deal of
stimulating and entertaining discussion, How a thing is to be
defined so as to exclude meanings which are not intended, but
which may, nevertheless, be legitimately included is a problem
most intelligent children will feel to be well worth tackling. For
example, a piece of household furniture consisting of a flat surface
1 Scimce and the Mvdem World (Cambridge University Press, 1925).